SPILSBURY: They don't look like humans at all. You know, often if you have a robot, you can see it's a guy in a suit. It's an actor. You know, it's very obvious. The thing with the Daleks is that they weren't obviously just an actor dressed up.

(SOUNDBITE FROM TV SHOW "DOCTOR WHO")

UNIDENTIFIED SPEAKER: Exterminate, exterminate, exterminate.

SPILSBURY: They're effectively a giant pepper pot, yeah.

BLOCK: In fact, it's been said that a pepper pot or salt shaker at a lunch meeting gave Ray Cusick the inspiration for the Daleks' look. They're supposed to be like tanks housing little green villains.

CORNISH: And Spilsbury says, in part, it's that look that made the Daleks a sensation in the 1960s.

SPILSBURY: Everything that you could put a Dalek on, Dalek cakes and Dalek jigsaws and Dalek - you know, everything. Anything you could put a Dalek on, it would sell. So, and to an extent, I think that's still true today. I mean, obviously it's fascinating that children in 2013 are still playing Daleks in the school playgrounds just as they were 50 years ago.

BLOCK: Ray Cusick's creations have stood the test of time. For 50 years, every time Doctor Who has defeated the Daleks, they have always come back to fight again. Transcript provided by NPR, Copyright NPR.